Ultra-short wave relay station



Sept. 19, 1933.

R. H. DARBORD ET AL ULTRA-SHORT WAVE RELAY STATION Filed July 10, 1931 3. Sheets-Sheet 1 RENE H. DARBORD ANDRE c. CLAVIER BY ATTORN EY Sept. 19, 1933. R, H, DARBQRD ET AL 1,927,394

ULTRA-530R? WAVE RELAY STATION 3 Sheets-Sheet 3 Filed July 10, 1931 FIG. 6

ngv ENTORS RENE H. DARBORD A DRE 0. CLAVIER /ZXQ ATTOR Y Patented Sept. 19, 1933 PATENT OFFICE.

ULTRA-SHORT WAVVE RELAY STATION Rene H. Darbord and Andre G. Clavier, Paris,

France, assignors to International Communications Laboratories, 1110., New.York, N. Y., a corporation of New York U Application July 10, 1931. Serial No. 549,930

10 Claims. (Cl. 2250-15) Our invention relates generally to the transmission of ultra short waves, and more particularly it relates t'othe transmission of ultra short waves between terminal stations that are optically invisible to one another without interference between the transmitting and receiving channels of the system.

-In ultra short Wave systems parabolic reflectors are employed to concentrate the ultra short waves for both transmission and reception. In direct transmission between a sending and a receiving station, it is, therefore, evident that a condition of optical visibility must exist between the parabolic reflectors at the two stations. In practice, howeven buildings, hills, or other obstructions frequently make it impossible to obtain the desired optical visibility. In such cases, therefore, direct transmission .of ultra short waves between a sending and a receiving station is impossible.

The most desirable solution of this difficulty is to provide a repeater station that is optically visible from both terminal stations.

' Accordingly, an object'of our invention is the provision of a repeater station optically visible from the two terminal stations by means of which two-way transmission can take place between two optically invisible terminal stations.

In the present system, separate parabolic reflectors are employed at each terminal station for transmitting ultra short waves to, and receiving them from, the repeater station. When the two reflectors at a terminal station are placed in the same plane and either side by side or at a small distance from one another, it has been found that interference occurs between the transmitting and receiving channels. A singing effect results from this interference.

Accordingly, another object of this invention is to avoid this undesirable singing effect by eliminating interference between the transmitting and receiving channels of the system.

In carrying out the last-mentioned object, it has been found necessary to orient the transmitting and receiving parabolic reflectors at each terminal station with their openings in a direction opposite to one another and at right angles to the direction of transmission, and toorient the transmitting and receiving parabolic reflectors in the same channel at the repeater station with their openings likewise in a direction opposite to one another and at right angles to the direction of transmission. With these orientations of the parabolic reflectors at the terminal stations and at the repeater station, interference between the transmitting and receiving channels is eliminated and the undesirable singing effectconsequently avoided.

If the above-mentioned orientations of the parabolic reflectors are made, it is evident that the geometry of two-way transmission between the optically invisible terminal stations then requires that plane reflectors be associated with the parabolic reflectors employed in. the system.

In carrying out the first-mentioned object it has been found desirable to provide different arrangements, one providing alternate two-way transmission between optically invisible termimission and reception. To this end means have been provided for automatic changing of the function of the high frequency tube from that of a transmitting tube to that of a receiving tube, when this change in function is required.

One of the principal features of our invention is the association of a plane reflector, having substantially a continuous surface, with each parabolic reflector'at the terminal stations and at the repeater station, in order to permit ultrashort wave two-way. transmission between these 'stations without interference between the transmitting and receiving channels.

Another principal feature is the orientation of the transmitting and receiving parabolic reflectors at each terminal station with their openings in a direction opposite to one another'and at right angles to the direction of transmission, in order to avoid interference between the transmitting and receiving channels of the system.

A further feature is the orientation of the transmitting and receiving parabolic reflectors in the same channel at the repeater station with their openings in a direction opposite to one another and at right angles to the direction of the transmission, for the purpose of eliminating interference between the transmitting and. receiving channels of the system.

Another featureis the substitution of screen gratings for the plane reflectors co-operating with the parabolic reflectors.

Another important feature" is a repeater sta- .tion for permitting alternate or simultaneous two-way transmission between two optically in-- visible terminal stations.

Another feature is the means for automaticalquency waves which 1y arranging the repeater station to retransmit to another terminal station upon the initiation of transmission between two terminal stations, even though the repeater station is normally conditioned for reception from both stations.

A further feature is the provision of a voiceoperated relay controlled by signals received at the repeater station for changing the reflecting electrode and/or the oscillating electrode voltage of a high frequency tube, thus conditioning the tube to act as a transmitting tube although it is normally prepared to act as a receiving tube.

Other objects and features will become apparent from a reading of the following description, taken -in connection with the accompanying drawings.

In order to define the type of ultra-high freit is proposed to pass through such relay stations, we shall consider that the ultra-high frequency oscillations have been modulated by one or more intermediate frequencies, and that these intermediate fre quencies have been modulated in turn by the voice frequencies corresponding to the several channels which it is proposed to transmit. It is to be understood in what follows, however, that any statements made withrespect to this double modulation system are equally applicable to a simpler system in which the voice frequency is allowed to modulate directly the ultra-high frequency oscillations.

Although various arrangements maybe used for the segregation of the signals proceeding along oppositely directed paths, as will appear in detail below, all the types of relay stations to be described below are characterized in common by the use of (1) a parabolic-reflector for concentrating the incoming waves on (2) the receiving antenna, (3) a receiving tube for demodulating the signals, (4) suitable amplifying apparatus for amplifying the demodulated signals, (5) means for placing the amplified signals on (6) a transmitting antenna, and ('7) a parabolic reflector for focusing the rays in the desired direction of retransmission.

Our invention is illustrated in the accompanying drawings wherein:

Fig. 1 shows the details of a relay station for alternate two-way transmission.

Fig. 2 is a modification of Fig. 1, wherein plane reflectors are used in connection with parabolic reflectors.

Fig. 3 shows a method for simultaneous twoway transmission using double plane reflectors in connection with parabolic reflectors.

; Fig. 4 is a modification of Fig. 3, wherein plane reflectors and screen reflectors are used in connection with parabolic reflectors.

Fig. 5 is a modification of Fig. 3, wherein two parabolic reflectors are used at both the receiving and transmitting side of the relay station.

Fig. 6 shows the details of a relay station designed to operate with the auxiliary apparatus of Figs. 3, 4 or 5.

In one form of our invention, illustrated in Fig. 1, the relay station is provided with two ultra-short wave tubes. as generators of very high frequencies for transmitting purposes, and also as. detectors of such high frequency waves, according to the value of These tubes may serve voltages applied to both the reflecting and the oscillating electrode are changed.

Such a tube has a cathode which is surrounded by a concentric reflecting electrode and an intermediate concentric helically arranged oscillating electrode. The reflecting electrode is maintained at a negative potential, the field of which reflects electrons emitted by the cathode. Electrons emitted from the cathode pass through the spaces between adjacent convulutions of the oscillating electrode reflected back through such spaces and, due to such passage direct and reflected, oscillations are set up along the oscillating electrode. These oscillations are led off through leads connected to the opposite ends of the oscillating electrodes.

Under normal conditions, the two tubes are in a receiving condition for the reception of waves arriving from the two opposite directions. When a wave arrives from the first terminal or sub-station, the detected current, suitably amplified, acts on a voice-operated relay which changes the value of the bias voltage applied to the reflecting electrode of the second tube, and/or the value of the positive high voltage applied to the oscillating electrode, thus placing this second tube in a transmitting condition. This arrangement is reversible and furnishes a very cheap transmission system.

When no signal is transmitted from the substations, the two tubes of the relay station automatically return to the receiving condition.

Referring to Fig. 1, the two tubes 1'7 and 27 are shown with their respective parabolic reflectors 15 and 25. Suitable amplifiers, well known in the art, are indicated at 19, 21, 29 and 31, while voice current relays are shown at 22 and 32.

These relays are connected to their respective amplifiers 19 and 29 by a path independent of the paths extending from 19 to 31 and from 21 to 29. It is only necessary to apply sufficient amplifier current to these relays to insure their operation. If desired, a delay network may be introduced to insure the operation of the relay in advance of the amplifier signal waves, in a manner well known in the art.

In order to change the function of a tube from that of a generator to that of a reflector, it simply requires a change in the voltage applied to y.

the reflecting electrode. As previous stated, however, the tube acts more efficiently as a transmitter if the voltage applied to the oscillation electrode is also changed.

Tubes 17 and 27 are normally in the receiving state. Consider a wave approaching from the left andhitting the reflector 15. The energy is concentrated in the doublet 16 which is connected to tube 1'7. The signal is detected and the audio frequency rectified signal is made to operate the voice-operated relay 22 after suitable amplification in 19. This relay in turn changes the plate voltage on the tube 2'7 so that it is placed in an operating condition suitable for retransmission. At the same time, the relay shorts the primary winding of transformer 28, rendering the system of the station inoperative for the reception of signals incoming from the right. The received signal, after being amplified in 19 and 31, is passed on to the grid of tube 2'7 and thence retransmitted to the right by means of the radiating element 26 and the reflector 25.

In this way, the system pictured allows only unflateral transmission at any given instant, but the system may be used for transmission in alternative directions at successive intervals of time.

Fig. 2 shows a modification of the station shown in Fig. 1, enablingthe axes of the paraboloidal reflectors to be oriented perpendicular to the direction of transmissioninstead of parallel, as in Fig. 1. By using this arrangement, the incoming rays maybe directed on to the reflecting face of the receiving paraboloid by revolution the plane reflector around a fixed axis.

Figs. 3, 4 and 5 represent different methods by which simultaneous transmission on several channels may be carried on between two terminal stations, .utilizing one intermediate relay station. It is to be understoodthat the number of relay stations may be increased indefinitely, each one'acting in a manner similar to the illustrative one described below. Fig. 6 represents the details of a relay station which may be used with the auxiliary apparatus pictured in either Figs. 3, 4 or 5.

Referring to Fig. 3, the terminal stations A and B are provided with parabolic reflectors 1 and 9 and plane reflectors3 and 11, respectively,v

at their transmitting ends and with parabolic reflectors 2 and 10 and plane reflectors 4 and 12, respectively.

The means for producing and receiving the high frequency waves are not shown, but it is to beunderstood that any suitable method may be used;

The details of the relay station interposed between the parabolic reflectors "I and 8 are shown in Fig. '6. The incident wave coming from one or the other of the terminal stations will fall on-an angular plane mirror 5 or 13. The receiving paraboloid 7 of the relay station thence receives energy. The receiving tube 57 detects the signals which, after having under- .gone suitable amplification,. serve to modulate the ultra high frequency oscillations generated by the transmitting tube 6'7. 1

Naturally, the retransmitting-tube sends a part of its energy in the incident direction. For

5 this reason it is necessaryto choose foreach direction of the path, modulation at a different intermediate frequency. The number of possible paths with the same frequency is thus decreased, but the carrier frequencyis so high that the system is still to be regarded as more favorable as contrasted with other radio transmission systems.

Another example more advantageous from the energy standpoint is illustrated in Fig. 4. The rays passing out from terminal station A are received by a reflecting plane 34 which is semiing of the wires may be so determined as to have the reflecting power and the transmitting power of the grating about equal.

The rays passing from B are received by the plane reflector 33, being partially transmitted -by the. grating 34 and arriving at the parabolic re- On the retransmitting end the set-up is similar. The figure assumes the transmitting antenna to be horizontal. The wires of the-grating 36, which is identical with the grating 34, are therefore horizontal. Rays retransmitted from 8 pass,

after'reflectiom-on to grating 36 and then pass out, after having crossed grating 36 and having been reflected by the plane receiver 35.

Naturally, as in the preceding, transmission passing from A arrives at B, but also returns to A. It is, therefore, neccssaryto utilize different intermediate frequencies on the two paths.

The loss factor for the field inthese systems; as compared with the use of a station with four paraboloids of equivalent dimensions, is compensated for to a considerable extent by the economic advantages of the system. This loss factor is, for example, :2 in the second of the systems. described above.

In the system last described, the direction of.

thewires of the reflecting grating is parallel to the plane containing the ray and the incident field. By inclining the direction of the wires with respect to this plane, it is easier to set up a grating which is semi-reflecting and semi-transparent. For examplathe wires of the grating will be at with the vertical or the planes of polarization will make an angle of 45 with the horizontal plane. 7

Among the principles for the setting up of terminal stations and relay stations which have been described, it is naturally possible to make a choice in accordance with circumstances. It would be interesting, for example, to adopt for the terminal stations the set-up which consistsin placing the plane of the paraboloids practically parallel to the direction of transmission and completing the installation with plane mirrors. On the one hand, a considerable economy on the extent of ground area necessary for the erection of they station may be realized, and, on the other hand, the rotation of the plane mirrors may be easily effected by mechanical means and permits the arbitrary variation of the direction of the beam in a simple manner.

Incidentally, a receiving station made in this way would constitute a direction-finding statio for ultra-short waves. I

As shown in Fig. 5, this set-up can be also applied advantageously in the case of a relay station where'it is preferable to utilize four paraboloids and four tubes, and hence have the possibility of utilizing, in the two senses, the whole range of .possible intermediate frequencies. It considerably reduces the complication of the relay station without developing undesirable interaction between the paths, and also diminishes, to a considerable degree, the cost of installation.

Fig. 6 represents a development of a repeater station for ultra-short waves for simultaneous,

transmission of several channels simultaneously in both directions.

Consider a series of doubly modulated waves coming from the left, as indicated by F1. These hit the left side of the double reflector 5 and are focused on the doublet 56. Demodulation takes place in the tube 57. The various intermediate.

frequencies pass into the filters 51, 52, where they are separated outand individually amplified in separate amplifiers 53, 54, etc. They may then be picked off by local audio frequency demodulators 63, 64, etc., or passed on through the lower 61, 62 filters and placed on the grid of the tube 67, where they modulate the ultra-high frequency oscillations and are reradiated from the antenna 66. Being focused by the reflector 8,

they pass to the reflectors 6-to 14 where they are partially reflected in the desired direction to the right, F1, and are partially. reflected along-the dotted path F2, and back to the left-hand terminalstation. It is assumed that here they are filtered out to eliminate possible interference.

What is claimed is:

1. In an ultra short wave system, two sources of polarized high frequency waves located at separated stations, a receiving parabolic reflector located at an intermediate station, a screen grating at the intermediate station positioned in the path of waves transmitted from one source for reflecting the incident waves therefrom to said parabolic reflector, and a plane reflector at the intermediate station positioned in the path of waves transmitted from the other source for reflecting the incident waves therefrom through said screen grating to said parabolic reflector.

2. In an ultra-short wave system, the combination of a terminal station and a repeater station between which alternate two-way trans mission can be carried on, said terminal station being provided with a transmitting parabolic reflector and a receiving parabolic reflector, having their openings opposite in direction, and the axis of said transmitting reflector being substantially at right angles to the direction of transmission from the terminal to the repeater station, and the opening of the receiving reflector being placed normal to the direction of transmission from the repeater to the terminal station.

3. In an ultra-short wave system, the combination of a terminal station having a transmitting parabolic reflector and a receiving parabolic reflector, a repeater station having a combination transmitting and receiving parabolic reflector associated with said terminal station, said transmitting and said combination reflectors having the axis of their openings at right angles to the directionof transmission from the terminal to the repeater station, said receiving reflector having the direction of its opening placed at an angle to the direction of transmission from the repeater to the terminal station, and a plane reflector having a substantially continuous metallic surface co-operating with eac parabolic reflector. i

4. In an ultra-short wave system, the combination of a first and a second terminal station each having a transmitting parabolic reflector and a receiving parabolic reflector, a repeater station having a combination transmitting and receiving parabolic reflector associated with each terminal station, the transmitting reflector at each terminal station and the combination reflector associated therewith having their openings directed at right angles to the direction of transmission from said terminal station to said repeater station, the receiving reflector at each terminal station and the combination reflector associated therewith having their openings directed obliquely to the direction of transmission between the repeater station and the terminal stations, and a plane reflector having a substantially continuous metallic surface co-operating with each parabolic reflector.

5. In an ultra-short wave system, the combinationof a flrst and a second terminal station each having a transmitting parabolic reflector and a receiving parabolic reflector, a repeater station having a combination transmitting and receiving parabolic reflector associated with each terminal station, each combination reflector'having the direction of its opening the same as the direction of the opening of the transmitting reflector and substantially opposite to the direction of the opening of the receiving'reflector at the associated terminal station, and a plane reflector having a substantially continuous metallic surface co-operating with each parabolic reflector.

6. In an ultra-short wave system, the combination of a repeater station having a source of high frequency oscillations,'a terminal station having a transmitting parabolic reflector and a receiving parabolic reflector and a source of high frequency oscillations, the transmitting reflector having the direction of its opening at right angles to. the direction of transmission from the terminal to the repeater station, the receiving reflector having the direction of its opening at right angles to the direction of transmission from the repeater to the terminal station, and a plane reflector having a substantially continuous metallic surface co-operating with each parabolic reflector, the plane reflector'associated with the transmitting reflector being adapted to reflect incident oscillations from said source and concentrated by said transmitting reflector at right angles to the axis of said reflector, and the plane reflector associated with said receivingreflector being adapted to reflect incident oscillations from the source at the repeater station to said receiving reflector in a direction parallel to its axis.

7. In an ultra-short wave system, the combination of a first and a second terminal station, each having a transmitting and a receiving parabolic reflector, a repeater station having a first parabolic reflector, means upon which waves from the transmitting reflectors at both terminal stations impinge and by which said impinging waves are directed to. said first parabolic reflector, a second parabolic reflector, and means including plane reflectors positioned in the path of the waves reflected by said second parabolic reflector and at suchangles to the path of said waves that the waves impinging upon the respective plane reflectors are thereby directed to the receiving reflectors at the respective terminal stations.-

8. In an ultra-short wave system, the combination of a pair of terminal stations, each having a transmitting parabolic reflector and a receiving parabolic reflector, a repeater station having a receiving parabolic reflector with its opening in the same direction as the opening of the transmitting reflectors at the terminal stations, and having a transmitting parabolic reflector with its opening in the same direction asthe receiving reflectors at the terminal stations, a plane reflector having a substantially continuous metallicsurface co-operating with each reflector at the terminal stations, and a double-surfaced plane reflector co-operating with each reflector at the repeater station.

9. In an ultra-short wave system, the combination of a pair of terminal'stations, each-having a transmitting parabolic reflector and a receiving parabolic reflector, a repeater station having a receiving parabolic reflector associated with the transmitting reflectors at the terminal stations,

and a transmitting parabolic reflector associated with the receiving reflectors at the terminal stations, all of said reflectors having the direction peater station. r

10. In an ultra-short wave system, a repeater station provided with a pair ofreceiving para-' bolic reflectors and a pair of transmitting parabolic reflectors, a first and a second terminal station each provided with a transmitting paraoperating with each parabolic reflector to satisfy bolic reflector and a receiving parabolic reflector, the geometrical requirements for two-way simulall of said reflectors having their opening directed taneous transmission between said terminal staat right angles to the direction of transmission tions and through said repeater station.

therebetween, and a plurality of plane reflectors one for each parabolic reflector and. each having a substantially continuous metallic surface co- RENE' 1. DARBORD. ANDRE G. CLAVIER. 

